Electronic structures and magnetic properties of (Ni,Al) co-doped 4H-SiC: A first-principles study

Based on density functional theory (DFT) first-principles method, we have investigated the electronic structures and magnetic properties of (Ni,Al) co-doped 4H-SiC system. Various configurations of Ni sites have been considered to confirm the most stable geometric construction. Comparing with pure 4H-SiC, the magnetic moment of Ni-doped 4H-SiC is increased, which is attributed to the hybridization of Ni:4s and C:2p orbitals. Moreover, we found that it is the 3d orbital of Ni that induces the spin-polarized state in Ni-doped 4H-SiC. In addition, the origin of ferromagnetic coupling between Ni-doped 4H-SiC has been predicted to be the ferromagnetic orders activated by the Ni-0:3d-C:2p-Ni-2:3d coupling chains. For (Ni,Al) co-doped system, we found that ferromagnetic stability is reduced significantly. For (2Ni, V-Si) co-doped 4H-SiC system, the antiferromagnetic state is more stable than ferromagnetic state with Delta E-FM of 97.2 meV, and the system changes from ferromagnetism to anti-ferromagnetism. These results provide a new route for the potential applications of dilute magnetic semiconductors in spintronic devices by employing doped 4H-SiC.